There has been a long-felt need for printable electronic components which may include semiconductors, metals, dielectrics, dopants, and/or any other material used in the fabrication of an electronic device, which may be deposited on a substrate. Compositions including such electronic material should have characteristics that allow for efficient printing applications, such as inkjet printing, gravure printing, offset lithography, screen printing, flexography, micro-spotting, pen-coating, stenciling, stamping, syringe dispensing, pump dispensing, spray-coating, slit coating, extrusion coating, meniscus coating, vapor-jet printing, etc. For example, in the area of printable dopants, a need is particularly felt for a printable dopant for forms of silicon and/or other semiconductors that are not easily or conveniently doped by ion implantation, e.g. for cost reasons or large area deposition of dopants, doped semiconductor films, etc.
Printed electronics require precise control of ink deposition volume in order to produce printed circuit features with the desired three dimensional morphological shape. Currently, most printed circuit masks are based on graphic arts printing masks. They typically use bitmapped image files (e.g., tagged image file format [TIFF], BMP, or other bitmapped image files) to describe the layout of one or more layers of a printed feature. Conventional printing devices generally produce an output pixel (e.g., an ink droplet, pattern of droplets, or other ink deposit) on the substrate for each pixel in the bitmapped image. However, printing one output pixel for each input pixel may result in an excessive volume of ink in some printed circuit applications. It would be desirable to more precisely control the volume of ink deposited onto the substrate.
Some conventional printing processes may rely on an absorbing substrate (e.g., paper or cloth) to fix a position and a size of a deposited material (e.g., an ink). Substrates typically used in manufacturing electronic devices are generally non-absorbing. The ink as printed on a non-absorbing substrate will behave as a liquid and will tend to move and/or spread until (or unless) the solvent is evaporated. Typically, the evaporation rate of the deposited ink is greatest near its edge, and liquid from the bulk of the drop tends to flow to the edge as evaporation occurs, resulting in deposition of solute particles near the edge. These and other characteristics of ink compositions deposited on various substrates present challenges and opportunities in the area of printable circuit design.
For example, there have been challenges in precisely controlling the printing of electronic materials over substrates and other features (especially high resolution silicon features). Conventional dielectric inks (e.g., sol-gel formulations for spin-on glasses, formulations for spin-on polymer coatings) are formulated to be compatible with spin coating, spray coating, slit coating, extrusion coating, etc. These inks often contain sol-gel materials. Typically, conventional liquid dielectric formulations contain volatile solvents (e.g., methanol or ethanol) and have low viscosity and low surface tension. This can result in dielectric layers that have undesirable cross-sectional profiles (e.g., a coffee-ring profile), thicknesses or thickness variations, film morphology, dimension control, etc. Dielectrics formed by printing conventional dielectric formulations on features (e.g. semiconductor films, metallic lines, etc.) may lead to enhanced electric field effects under certain operating voltages in areas where the dielectric layer is too thin, which can result in premature breakdown and leakage. Additionally, defects may result in films that are printed using conventional dielectrics, such as an undesirable roughness (an “orange peel” appearance). When they are used in an inkjet printing process, the dielectrics may cause clogging of and/or contamination in the inkjet nozzles due to evaporation of the high volatility solvents.
Advances in the art provide for improvements in spreading characteristics of the printed ink in order to effectively cover certain features, such as semiconductor device features (e.g., source/drain terminal regions, gates, metal lines, capacitor and/or diode plates, etc.) on a substrate on which the dielectric is printed. Too little spreading may result in incomplete coverage of the features (e.g., source/drain terminals may be insufficiently covered to adequately dope the underlying semiconductor), and too much spreading may result in inadvertent coverage of regions intended to be exposed (e.g., contact regions to the source, drain, and gate), which may disrupt the subsequent formation of further circuit structures (e.g., contacts to the source and drain), or inadequate coverage of features having relatively high topological variability (e.g., channel/gate crossovers).
However, even with advances in the spreading characteristics of deposition compounds, when printing on non-porous substrates such as steel, silicon (Si) wafers polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc., one drop, cell, or other printable unit corresponding to a pixel in the initial image may spread to produce the equivalent of three or more pixels in length and width. Furthermore, the ink deposited may or may not have the proper 3-D profile. Conventional image file standards generally do not specify the necessary corrections required to obtain the desired length, width, height, and 3-D profile of materials printed on a non-porous substrate.
Therefore, it is desirable to provide methods and software for making appropriate corrections to image-based circuit layouts produced by conventional circuit design and layout editing software in order to facilitate printing onto non-porous substrates.